With the ever-growing need for wireless communications, wireless spectrum resources continue to come under increasing pressure. Recently, cognitive radio (CR) technology has been proposed to increase the efficiency of spectrum utilization by providing for dynamic spectrum resource management Indeed, such resource management may allow users to use portions of licensed spectrum resources that are not being fully exploited by their primary users at particular times and locations. Accordingly, by adopting dynamic spectrum resource management, the CR system may provide for the use of unoccupied spectrum segments, while guaranteeing the rights of primary users.
In order to allocate unused spectrum resources, the CR systems must include a spectrum sensing technique to accurately and quickly identify the spectrum usage status over a wide frequency range covering various communication standards. Moreover, the spectrum sensing techniques are preferably consume little power and are easy to implement.
Prior spectrum-sensing techniques can generally be categorized into two groups—(1) energy detection and (2) feature detection. However, both of these spectrum sensing techniques are not ideal for use in a CR system. Indeed, energy detection spectrum sensing techniques require careful selection of one or more threshold levels and are oftentimes vulnerable to noise and noise-like broadband digital modulated signals. Likewise, feature detection spectrum sensing techniques require longer processing times, excessive digital hardware resources, and large power consumption.